The present invention relates generally to optoelectronic switching apparatus, and more particularly, to an optoelectronic multibit switching apparatus that may be used in beamsteering applications.
The present invention provides an improvement of an optoelectronic switch designed for beamsteering applications that is disclosed in U.S. Pat. No. 5,109,449, assigned to the assignee of the present invention. This patent discloses a variable optical delay line that is employed with a laser transmitter, an optoelectronic switch, and an analog variable delay line to provide a controllable delay path for applied RF energy transmitted or received by an active array of antenna elements. The variable optical delay line comprises a input optical fiber that transmits an RF modulated optical signal to a plurality of output optical fibers. Each output fiber has a different length that determines the propagation delay of the modulated optical signal therethrough. The optoelectronic switch is responsive to the optical energy provided by a selected one of the second fibers. The switch detects the delayed optical energy and couples it to the analog variable delay line, and thereafter to a selected antenna element of the array, for example.
The optoelectronic switch of U.S. Pat. No. 5,109,449 has greater loss and/or greater complexity than is desirable for some applications because it uses only one type of switching apparatus; either laser switches or photodiode detector switches. For true-time-delay beamsteering, this requires a larger number of cascaded stages than is desirable for some applications to achieve a given number of delays.
The need for reconfigurable high speed circuits and in true-time-delay beam-steering for active arrays is recognized for both military and commercial applications. The use of fiber optics for many types of applications is expected to increase in the future. Thus, as the use of fiber optics increases, the need for circuits that can optimally reconfigure electronic circuits and provide usable delays for beamsteering will also increase. The present invention is designed to meet these needs.
Therefore, it is an objective of the present invention to provide an improved optoelectronic switching apparatus. It is another objective of the present invention to provide an improved optoelectronic switching apparatus that may be used for multibit beamsteering applications. It is a further objective of the present invention to provide an optoelectronic switching apparatus that provides a relatively large number of interconnects while maintaining a relatively low insertion loss when compared with conventional devices.